Because the current process of re-profiling tenons while the buckets are installed on the rotor is an all manual process the variance of tenon shape from bucket to bucket can vary quite substantially. The quality of the profile may vary significantly depending on the skill of the operator and ability to grind the tenon sufficiently accurately to match the template. The tenons may not be ground to the proper shape, or may be damaged by improper manual grinding techniques. Grinding tenons manually is also a time consuming process which may in some instances require up to 80 man hours to complete the grinding of a single row of buckets on a turbine. With the robotic system the tenons may be machined to precisely match the drawing. The sides of the tenon are positioned perpendicular to the vane tip.
With the current processes used for machining tenons, for bucket tenons to be lengthened the turbine rotor must be installed into a turning device or lathe. The tenons tips are machined with a carbide or high speed tool bit. The current machining process allows for machining on either side of the tenon, but not directly on the top or bottom of the tenon. Material that is unreachable for machining must be dressed manually with pneumatic grinding machines. Like re-profiling the quality of manual grinding or dressing is highly dependent on the skill level of the operator.
With a robotic system the rotor is not placed into a turning device or lathe. A robotic controller guides a robotic arm and spindle around the tenon and bucket tip and removes a prescribed amount of tenon material. Tenon material may be removed on the entire tip of the vane in a single setup. Machining robotically will provide substantially identical profiles or shapes on each bucket, since the vision system locates the cut path based on the geometry of the vane.